Composite containers are utilized for packaging a variety of products including food products, powdered products, etc. There is always a need to improve such composite containers, particularly from the standpoint of product differentiation, packaged product protection and ergonomics.
It has been determined by this invention that a composite container of this general type could be improved by providing such composite container with a recessed spiral groove extending around the container for the length of the container. The benefits of such a container construction would be generally, as follows.
Firstly, a spiral groove in such a composite container would be ascetically different from current composite container designs or constructions. This geometric design feature would warrant the attention of consumers to a greater extent than just graphics placed on such a composite container. Secondly, the geometry of a recessed spiral groove in such a composite container would provide greater resistance to rupture and better cushioning from side impact of a filled container. Side impact on a composite container without such inwardly grooved construction can cause a rupture in the container wall. A rupture could naturally contaminate the product, cause the product to spoil or even cause the product to spill. Very fragile items could also receive greater protection from the cushioning or dampening effect of the recessed grooves over a conventional straight walled container. Another benefit of a composite container with recessed spiral grooves is one of ergonomics. A composite container that has recessed grooves is easier to grasp and hold than a straight walled container. Larger diameter containers can be handled much easier and safer with the presence of recessed spiral grooves.
In accordance with this invention, it has been determined that such an improved composite container could preferably comprise at least one spirally-wound paperboard bodywall layer in strip form defining a substantially cylindrical container having opposed ends, a liner layer in strip form spirally-wound inside the bodywall layer in superimposed position therewith, and at least one recessed spiral groove formed in the superimposed bodywall layer and liner layer and extending around the cylindrical container along its length and being positioned at an angle to a longitudinal axis of the container which corresponds to a winding angle of the spirally-wound container. It has also been found desirable to incorporate a plurality of closely-spaced spiral grooves positioned at an angle to the longitudinal axis of the container for forming a spaced group of spiral grooves around the cylindrical container along its length. The container may further comprise a label layer in strip form spirally-wound around the outside of the bodywall layer in superimposed position therewith and having the recessed spiral groove formed therein.
This novel composite container construction has not heretofore been thought possible or practical from a manufacturing standpoint inasmuch as current spiral winding equipment for such composite containers does not allow for inward grooves in the bodywall of the composite container due to the solid geometry of the mandril used therein and the process requirement that the material being spirally-wound must spiral down the mandrel as the container is being made. Accordingly, in accordance with this invention, a process for manufacturing a cylindrical composite container having a recessed spiral groove therein has been developed and comprises generally the following steps.
A mandrel is provided which has at least one recessed spiral groove cut into its surface and positioned at a predetermined angle to a longitudinal axis of the mandrel. Desired layers of material for constructing the composite container are provided and are fed onto the mandrel while spirally winding such material layers at a winding angle corresponding to the predetermined angle of the spiral groove in the mandrel to form a continuous tube of the material layers on the mandrel. External pressure is applied at the mandrel spiral groove to the continuous tube as it is being formed to force the material layers into the spiral groove for deforming the material layers to form a spiral groove in the continuous tube. The continuous tube with spiral groove therein is then cut into individual container lengths and these container lengths are removed from the mandrel to form individual composite containers.
The mandrel may preferably include a plurality of closely-spaced spiral grooves positioned at a predetermined angle resulting in a spaced group of spiral tubes around the mandrel to form a spaced group of spiral grooves around the manufactured composite container.